High-Fiber Extruded Purple Sweet Potato (Ipomoea batatas) and Kidney Bean (Phaseolus vulgaris) Extends the Feeling of Fullness

Low intake of dietary fiber is closely related to an increased risk of various non-communicable diseases globally. This study aimed to develop a formulation for high-fiber extrudate based on purple sweet potato and kidney bean and evaluate the nutritional value of the products and their satiety index after consumption. Optimization of the formula was carried out using four levels of purple sweet potato flour substitution with kidney bean flour: 0, 20, 30, and 40% ( w/w ). The extrudates were obtained using a double-screw extruder at 60°C, with the auger, screw, and cutter speeds of 40, 40 and 50 Hz, respectively. The satiety index determination involved 16 subjects with body mass index in optimal range, and data from the visual analogue scale (VAS) questionnaire were used at 0, 30, 60, 90, 120, 150, and 180 min after consumption of the test food. The product with the highest substitution (40%) of kidney bean was selected as the best based on the sensory acceptability and nutritive value – contents of protein and total fiber were 13.20 and 17.00 g in 100 g dry matter, respectively. The estimated shelf-life of this extrudate was 19 months. Satiety index values for commercial cereals, extruded purple sweet potato, and extruded purple sweet potato with kidney bean were 99, 104, and 140, respectively. This research showed that the consumption of high-fiber extruded sweet potato with kidney bean could significantly extend the feeling of fullness with low energy contribution so that it might prevent excess calorie intake contributing to overweight and obesity.